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Abstract The qRT-PCR technique has been regarded as an important tool for assessing gene expression diversity. Selection of appropriate reference genes is essential for validating deviation and obtaining reliable and accurate results. Lotus (Nelumbo nucifera Gaertn) is a common aquatic plant with important aesthetic, commercial, and cultural values. Twelve candidate genes, which are typically used as reference genes for qRT-PCR in other plants, were selected for this study. These candidate reference genes were cloned with, specific primers designed based on published sequences. In particular, the expression level of each gene was examined in different tissues and growth stages of Lotus. Notably, the expression stability of these candidate genes was assessed using the software programs geNorm and NormFinder. As a result, the most efficient reference genes for rootstock expansion were TBP and UBQ. In addition, TBP and EF-1α were the most efficient reference genes in various floral tissues, while ACT and GAPDH were the most stable genes at all developmental stages of the seed. CYP and GAPDH were the best reference genes at different stages of leaf development, but TUA was the least stable. Meanwhile, the gene expression profile of NnEXPA was analyzed to confirm the validity of the findings. It was concluded that, TBP and GAPDH were identified as the best reference genes. The results of this study may help researchers to select appropriate reference genes and thus obtain credible results for further quantitative RT-qPCR gene expression analyses in Lotus.

Abstract Seals are well‐known for their remarkable hydrodynamic trail‐following capabilities made possible by undulating flow‐sensing whiskers that enable the seals to detect fish swimming as far as 180 m away. In this work, the form‐function relationship in the undulating whiskers of two different phocid seal species, viz. harbor and gray seals, is studied. The geometry and material properties of excised harbor and grey seal whiskers are systematically characterized using blue light 3D scanning, optical and scanning electron microscopy, and nanoindentation. The effect of the undulating geometry on the whiskers’ vibration in uniform water flow is studied using both experimental (piezoelectric MEMS and 3D‐printed piezoresistive sensors developed in‐house) and numerical (finite element method) techniques. The results indicate that the dimensionless ratio of undulation wavelength to mean whisker diameter (λ/Dm) in phocid seals may have evolved to be in the optimal range of 4.4–4.6, enabling an order‐of‐magnitude reduction in vortex‐induced vibrations (compared to a similarly‐shaped circular cylinder) and, consequently, an enhanced flow sensing capability with minimal self‐induced noise. The results highlight the importance of the dimensionless λ/Dm ratio in the biomimetic design of seal whisker‐inspired vibration‐resistant structures, such as marine risers and wake detection sensors for submarines.

Can a robotic gripper only operate when attached to a robotic arm? The application space of the traditional gripper is limited by the robotic arm. Giving robot grippers the ability to move will expand their range of applications. Inspired by rich behavioral repertoire observed in octopus, we implement an integrated multifunctional soft robotic gripper with 6 independently controlled Arms. It can execute 8 different gripping actions for different objects, such as irregular rigid/soft objects, elongated objects with arbitrary orientation, and plane/curved objects with larger sizes than the grippers. Moreover, the soft gripper can realize omnidirectional crawling and swimming by itself. The soft gripper can perform highly integrated tasks of releasing, crawling, swimming, grasping, and retrieving objects in a confined underwater environment. Experimental results demonstrate that the integrated capabilities of multimodal adaptive grasping and omnidirectional motions enable dexterous manipulations that traditional robotic arms cannot achieve. The soft gripper may apply to highly integrated and labor-intensive tasks in unstructured underwater environments, including ocean litter collecting, capture fishery, and archeological exploration.

With the continuous development and expansion of the water reclamation and reuse market, it is vital to ensure water quality safety and stability over the entire water reuse system. Because the quality of reclaimed water is distinct from that of drinking water, it is likely to deteriorate, even after advanced treatment, during distribution and transport. This review identifies the common microbial corrosion in reclaimed water distribution pipelines and end use applications (e.g. industrial cooling system) and the dominant corrosive microorganisms in reclaimed water. The microbial corrosion mechanism and the affecting factors on microbial corrosion are discussed in depth. Moreover, this study also proposes possible strategies for dealing with pipeline microbial corrosion, including the control of the assimilable organic carbon content via coagulation and filtration processes as well as disinfection technologies for microbial inactivation. This study is of great novelty to provide a comprehensive overview of microbial corrosion in reclaimed water distribution and application and point out future directions towards sustainable and long-lasting water reuse. HIGHLIGHTS Reclaimed water technology;; Microbial corrosion;; Pipeline materials;; Control strategies;

Abstract We propose that the asymmetry-induced tunneling electroresistance (TER) effect in a ferroelectric tunnel junction (FTJ) could be improved by integrating a polarization-controlled resonant band. Using first-principles calculations and a quantum-mechanical tunneling model, we studied an asymmetric FTJ SrRuO3/BaTiO3/SrTiO3/SrRuO3. The resonant band is integrated into this FTJ by two atomic layers of BaSnO3 embedded in the barrier. In the elaborated FTJ SrRuO3/BaTiO3/BaSnO3/SrTiO3/SrRuO3, both resonant band and asymmetry work together. For one polarization direction, the BaSnO3 and SrTiO3 dielectric layers work together as barriers to provide considerable efficient barrier height for direct tunneling and lead to large tunneling resistance. For the opposite polarization, the BaSnO3 layer serves as a quantum well to induce resonant tunneling across the barrier and considerably reduces the tunneling resistance of the ON state. The integration of resonant band with asymmetry may provide a more efficient and applicable way to further improve the functionalities of FTJs.

Abstract A soft gripper inspired by the glowing sucker octopus (Stauroteuthis syrtensis)’ highly evolved grasping capability enabled by the umbrella‐shaped dorsal and ventral membrane between each arm is presented here, comprising of a 3D‐printed linkage mechanism used to actuate a modular mold silicone‐casting soft suction disc to deform. The soft gripper grasp can lift objects using the suction generated by the pump in the soft disc. Moreover, the protruded funnel‐shaped end of the deformed suctorial mouth can adapt to smooth and rough surfaces. Furthermore, when the gripper contacts the submerged target objects in a turbid environment, local suctorial mouth arrays on the suction disc are locked, causing the variable flow inside them, which can be detected as a tactile perception signal to the target objects instead of visual perception. Aided by the 3D‐printed linkage mechanism, the soft gripper can grasp objects of different shapes and dimensions, including flat objects, objects beyond the grasping range, irregular objects, scattered objects, and a moving turtle. The results report the soft gripper's versatility and demonstrate the vast application potentials of self‐adaptive grasping and sensing in various environments, including but are not limited to underwater, which is always a key challenge of grasping technology.

Al–air battery has been regarded as a promising new energy source. However, the self-corrosion of aluminum anode leads to a loss of battery capacity and a decrease in battery longevity, limiting its commercial applications. Herein, indole-2-carboxylic acid (ICA) has been added to 4 M NaOH as a corrosion inhibitor. Its impact on the self-corrosion of aluminum alloy and the enhancement of the functionality of Al–air batteries at various concentrations have been investigated. X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM) techniques have been used to examine the compositional and morphological alterations of aluminum alloy surfaces. Electrochemical and hydrogen evolution tests showed that indole-2-carboxylic acid is an efficient corrosion inhibitor in alkaline solutions, and its impact grows with concentration. Our findings demonstrated that when the inhibitor concentration is 0.07 M, the inhibition efficiency is 54.0%, the anode utilization rises from 40.2% to 79.9%, the capacity density increases from 1197.6 to 2380.9 mAh g−1, and the energy density increases from 1469.9 to 2951.8 Wh kg−1. In addition, theoretical calculations have been performed to support the experimental results.

Photo-assisted sol–gel route was developed to prepare nanostructured Li4Ti5O12 anode materials. Resulting Li4Ti5O12 powders were characterized by phase analysis, microscopic morphology observation, and cyclic charge/discharge tests. As lithium-ion battery electrode, synthesized Li4Ti5O12 material by using the photo-assisted sol–gel route shows specific capacity of 120 mAh g−1 at 10C discharge rate. Furthermore, this material retains 98% of its initial specific capacity at 0.2C after 50 charge/discharge measurements. Outstanding rate capability and cycling stability of this Li4Ti5O12 material are mainly derived from grain refinement induced by ultraviolet photo-irradiation. Therefore, this photo-assisted sol–gel route is attractive alternative method for preparing electrode materials for high-power lithium-ion battery applications.

Although artificial Lieb lattices have been recently synthesized, the realization of a Lieb lattice in a real material is still challenging. Here the authors use tight-binding and first principle calculations to predict tunable topology and magnetism in recently discovered two-dimensional covalent-organic frameworks.

As the largest group of structurally diverse metabolites, terpenoids are versatile natural compounds that act as metabolism mediators, plant volatiles, and ecological communicators. However, few terpenoid compounds have been identified in plant parts of sacred lotus (Nelumbo nucifera Gaertn.). To elucidate the molecular genetic basis of the terpene biosynthetic pathway, terpenes from different parts of the plant, including seeds (S), young leaves (YL), mature leaves (ML), white flowers (WF), yellow flowers (YF), and red flowers (RF), were identified by LC-MS/MS and the relative contents of the same terpenes in different parts were compared. The results indicate that all plant parts primarily consist of triterpenes, with only minor quantities of sesquiterpenes and diterpenes, and there were differences in the terpene content detected in different plant parts. To illustrate the biosynthesis of various terpenoids, RNA sequencing was performed to profile the transcriptomes of various plant parts, which generated a total of 126.95 GB clean data and assembled into 29,630 unigenes. Among these unigenes, 105 candidate unigenes are involved in the mevalonate (MVA) pathway, methyl-erythritol phosphate (MEP) pathway, terpenoid backbone biosynthesis pathway, and terpenoid synthases pathway. Moreover, the co-expression network between terpene synthase (TPS) and WRKY transcription factors provides new information for the terpene biosynthesis pathway.

Abstract The inhibition performance and mechanism of loquat leaves extract (LLE) for the corrosion of mild steel in 0.5 M H2SO4 were investigated using weight loss method, electrochemical measurements and scanning electron microscope (SEM). The results revealed that LLE acted as a modest cathodic inhibitor, its inhibition efficiency increased with the concentration of LLE and reached a maximum value of 96% at the 100% V/V concentration, but decreased with incremental temperature. Besides, it was found that the adsorption of LLE on steel surface obeyed Langmuir adsorption isotherm, and then the thermodynamic and kinetic parameters were further determined accordingly. Furthermore, LLE was preliminarily separated by pH-gradient sedimentation and the synergistic inhibition between the isolates was investigated.

Plasma discharging treatment (hydroxylation) was conducted on copper surfaces for the subsequent electro-polymerization procedure of polypyrrole (PPy) coating (d-PPy). The hydroxylated surface could solve the criticized adhesion strength and protection efficiency of electropolymerized coatings for metal substrate in corrosive media. Compared with the counterpart obtained via passivation pretreatment (p-PPy), a well-adhered d-PPy layer was acquired on the hydroxylated copper surface, which earned a satisfactory adhesion grade, compactness and conductivity. Appreciable protection of d-PPy was measured for copper in the artificial seawater (ASW) at 298 K via electrochemical and surface analyses. Results of electrochemical measurements indicated that d-PPy coating effectively retarded copper corrosion in ASW with a lowered corrosion current density and improved charge transfer resistance. Surface analysis revealed that the typical morphology of PPy was retained after 240 h immersion in ASW. A favorable physical barrier and anodic protection efficacy might account for the superior protection of d-PPy coating for the underlying copper. Molecular dynamics simulations for the deposition of PPy chains on pristine and hydroxylated copper planes provided a definite correlation between the theoretical calculations and experimental observations. Theoretical modelling also disclosed in-depth the anchoring nature and anticorrosive mechanism for PPy toward the hydroxylated copper in ASW.

Background Starch branching enzyme (SBE) is one of the key enzymes in starch biosynthetic metabolism, determining amylopectin structure. Methods Full length coding sequences (CDS) of SBE genes were cloned using reverse transcription PCR (RT-PCR) technology, and neighbor-joining (NJ) tree was used for phylogenetic analysis. Single nucleotide polymorphisms (SNPs) were determined to assess the genetic polymorphisms and variation indexes between individuals and clusters. Quantitative real time PCR (qRT-PCR) was performed to analyze the spatial and temporal expression of NnSBE genes. The effect of NnSBE genes on amylopectin’s fine structures was explored using affinity and the enzyme activity analysis of two isoforms in amylopectin and amylose. Results In this study, two SBE family genes, NnSBEI and NnSBEIII, were identified in lotus (Nelumbo nucifera Gaertn.). Phylogenetic analysis sorted NnSBEI into SBE family B and NnSBEIII into SBE family A. UPGMA phylogenetic tree divided 45 individuals of lotus into three classes. The homozygous haplotype (A G G A G) of NnSBEIII was observed in seed lotus. During the seed embryo development stage, NnSBEIII reached the peak in the middle of the development stage, while NnSBEI increased in the mid-late developmental stage. The different affinity activity of the two isozymes binding amylopectin and amylose assay indicated NnSBEI has higher activity and wider affinity. Discussion Genetic diversity showed that NnSBE genes received artificial selection during the process of cultivation and domestication in lotus seeds. Furthermore, the expression pattern and affinity activity analysis indicated that NnSBE genes were related to the chain length of amylopectin.

Here, S-allyl-O,O′-diphenyldithiophosphate(SOD1), S-allyl-O,O′-dibenzyldithiophosphate (SOD2) and S-allyl-O,O′-di(2-phenylethyl)dithiophosphate(SOD3) were successful synthesized and characterized, which acting as the novel corrosion inhibitors for mild steel in hydrochloric acid (HCl) solution were evaluated by electrochemical measurements, weight loss measurement and scanning electron microscopy. Potentiodynamic polarization measurement indicates that the synthesized inhibitors are effective mixed-type inhibitors. The inhibition efficiency increases with inhibitor concentration increasing, decreases with HCl concentration and temperature increasing. The adsorption of SOD1, SOD2 and SOD3 on mild steel surface obeys Langmuir isotherm. The adsorption of SOD1 and SOD3 on mild steel surface is a mixed adsorption involving both physisorption and chemisorption, and that the adsorption of SOD2 on mild steel surface belongs to chemical adsorption. Keywords: Corrosion inhibitor, Mild steel, Polarization, Weight loss, Adsorption

The development of new signal systems for electrical biosensors could provide exciting new opportunities for biomedical analysis, pollutant monitoring, and explosive detection. The signal systems for commercial portable sensors involve the integration of a battery and a circuit conditioning system to power an amperometric biosensor. However, this increases the size and complexity of the entire system. In this study, we develop a simple amperometric biosensor that is directly powered by a button cell battery for the detection of lactate. A two-electrode sensing transducer was printed on cardboard or integrated on a ring. It was directly powered by a button cell battery, and connected to a multimeter for current measurement. This sensor showed a sensitive detection range of 0.04762-9.21429 mM and short measuring time of 2 min. These results show that this system can achieve an excellent sensing performance, and the construction of this new sensing system directly powered by a button cell battery offers a new method for further developing a wide range of miniaturized, flexible, portable, or wearable sensing systems, and these could be used in detecting various analytes that are important in medical diagnosis and environmental monitoring.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Liquid metal MHD (Magneto-Hydro-Dynamic) systems can be employed to produce electricity from a wide range of heat resources. In such a system, a low-boiling organic fluid and a high-temperature liquid metal fluid mix. The former evaporates, and carries the latter to flow through an MHD channel, where the electricity is generated. The mixing process and the gas-liquid flow characteristics will have a significant effect on the power generating efficiency. In the present work, trifluorotrichloroethane (R113) was chosen as the organic fluid, and gallium (Ga) as the liquid metal, respectively. Numerical study was subsequently carried out on the gas-liquid flow and heat transfer in a self-designed spherical mixer. The effects of the main factors, including the inlet velocities and inlet temperatures of Ga and R113, were separately determined, with suggested values or ranges discussed in detail.